1. Field of the Invention
The present invention relates to image display apparatuses, image processing apparatuses, and image display methods.
2. Description of the Prior Art
Display devices such as liquid crystal displays, plasma displays, electroluminescence (EL) displays, and digital mirror devices (DMD), which modulate, by mirror reflection or optical interference, pixels discretely arranged in a matrix to display images, are employed in various image display apparatuses such as flat-panel televisions and projection televisions as well as projectors and monitors for computers. These display devices having pixels arranged in a matrix can be classified into a hold type display that uses a liquid crystal or EL with an active matrix drive circuit and a pulse-width-modulation type display that uses plasma or a DMD to produce gray-levels by varying duration of illumination or exposure, which are distinguished from an impulse type display that uses a cathode ray tube (cold cathode ray tube or Braun tube). In the hold type display and the pulse-width-modulation type display, when motion pictures are viewed, deterioration in image quality—most notably as motion blur—may sometimes occur due to deviation between movements of the display-position of a moving object and the human viewpoint. Hence, an image processing method has been disclosed for improving such displays, in which interpolated frames are interposed between temporally neighboring frames to improve image quality (for example, refer to Japanese Patent Application Publication No. 2004-357215, par. [0017] and FIG. 2).
In recent years, on the other hand, a wide spread of high-definition broadcasting and a significant increase in computer processing speed have propelled displays to rapid progress toward high definition. While display devices have also developed toward high definition along with these movements, the progress of display devices toward high definition not only needs high processing accuracy but also is a factor that contributes to increasing manufacturing costs due to reduction in yield and the like. In such situation, a method has been disclosed in which a high-definition image is displayed by an image display unit having fewer pixels than those contained in an inputted image using a display technique of pixel shifting or wobbling (for example, refer to Japanese Patent Application Publication No. H10-210391, par. [0018] and FIG. 3).
The image processing method that interposes interpolated frames as described above needs to increase the number of images displayed per second by increasing the frame frequency. For that reason, there has been a problem that causes increase of the transmission amount of image signal and complexity of the circuit configuration.
In particular, employing a display technique of shifting pixels in such image processing method needs to generate split sub-frames of interpolated frames for the pixel shifting, which has posed a problem that causes, to a greater extent, increase of the transmission amount of image signal and complexity of the circuit configuration.